Rotax chains coming off

Matt France · Joined: 21 Jun 2002 Posts: 106

How soft are you running your kart?
We had one driver where i race throwing chains because of chassis flex.

BTW We race on a really bumpy track.

Drew Cleaver · Posted: Mon Jul 01, 2002 5:38 pm Post subject: Rotax chains coming off

Why not run a 13 or 14 and run a smaller rear gear?

Bob Adams · Posted: Mon Jul 01, 2002 8:03 pm Post subject: Rotax chains coming off

Drew needs a class in simp;e math. By upper the number of driver teeth you will need to increase the number of driven teeth to get to the same ratio, I.E. the driven sprocket diameter will have to increase.

Chad Stapleton · Joined: 19 Jul 2001 Posts: 4403

12:90+ ? you must have one tight track !
Even so, unless you are actually hitting the sprocket on the track, it should not jump off.
If you are "bottoming" the sprocket, you could fit a skid-plate under it.

Blair Lechtenberg · Joined: 09 Apr 2002 Posts: 5 Location: Castaic,Ca.

If you're not hitting the track surface,the only thing I can think of is to make sure you have a tensioner bolt between the bearing cassette and the back motor mount.Set the chain tension about 1/2" ,snug the bolt and tighten the retaining nut-tight.
Before I installed one,the motor would slip back no matter how tight the mounts were. That's the price for all that Rotax horsepower! Hope it helps.

Shannon Schmidt · Posted: Mon Jul 01, 2002 10:19 pm Post subject: Rotax chains coming off

Is anyone else out there having a hard time keeping their chain on? Our track is very rough and this problem has befallen many a Rotax racer. We all started with a 12 tooth pinion and were running big gears on the back (90 and above). Many of us were hitting the track with sprocket, so we have switched to an 11 tooth pinion. Its seems to have helped, but it still crops up every once in a while. If anyone has any tips it would be appreciated!

[ July 01, 2002: Message edited by: Shannon Schmidt ]

Mary-Ann Horley · Posted: Tue Jul 02, 2002 12:14 am Post subject: Rotax chains coming off

you could put sprocket guards on the rear sprocket

Drew Cleaver · Posted: Tue Jul 02, 2002 5:59 am Post subject: Rotax chains coming off

Maybe I'm confused but....
Bigger on the front is for more top end. Smaller on the Rear is more top end. Smaller on the Front is more bottom end. Bigger on the rear is more bottom end. Therefore you go to a 14 giving you more bottom end and less top, so to get your top end back you use a smaller rear gear.

Bruce Woodrow · Posted: Tue Jul 02, 2002 7:41 am Post subject: Rotax chains coming off

You're very confused.

Matt Cleaver · Posted: Tue Jul 02, 2002 7:43 am Post subject: Rotax chains coming off

quote:
Originally posted by Drew Cleaver:
Maybe I'm confused but....

Drew, Drew, Drew. Don't worry folks, luckily Drew isn't the brains of our operation, he's just the ace driver.

The gear ratio is just that, a ratio. Therefore in order to keep the ratio the same, if one sprocket gets smaller, so must the other. To use your terminology, if you put a smaller on front, you have more "bottom end." Therefore to offset all the "bottom end" you put a smaller on the rear, which gives more "top end," and hopefully and up with close to the same ratio. It's OK bud, just drive.

Rick Beilfuss · Posted: Tue Jul 02, 2002 7:59 am Post subject: Rotax chains coming off

If you really want to get confused - Go to 4cycle.com and read the page after page arguments about using a ratio with small gears versus the same ratio with large gears.

Rick

Rick Beilfuss · Posted: Tue Jul 02, 2002 8:02 am Post subject: Rotax chains coming off

I agree with the sprocket guards. Back when I raced Briggs, I used a double aluminum guard. Not only did it protect the gear and chain on excursions, but the chain stayed on no matter how much slop or misalingnment was in the chain.

Jeff Edwards · Joined: 10 Sep 2001 Posts: 193

In addition to chain tension, don't forget the all important alignment. So many karters think they've got the sprockets aligned, but hold a straight edge to them and !!!

Also, if your rear axle has side to side play, guess what this does to alignment on that next corner you're powering around...

Jeff Edwards

Shannon Schmidt · Posted: Tue Jul 02, 2002 6:29 pm Post subject: Rotax chains coming off

Thanks everyone for the replies. At least I fell a bit beter that I am not the only one this is happening to. I think my problem is that the hub is not perfectly centered and a few of my sprokets are old. Plus I think I have had the chain tension too tight, if that is possible. Good luck to everyone and thanks again.

Dick George · Posted: Tue Jul 02, 2002 10:19 pm Post subject: Rotax chains coming off

My chain flings itself off with amazing regularity! But since I'm having so many other problems with this future boat anchor, its often a welcome relief! Blair is probably right about the bolt thing though.